Removal of warp from corrugated paperboard

ABSTRACT

A new method and apparatus is provided by this invention for removing the warp from warped sheets of corrugated paperboard in corrugated box plants. In accordance with this invention, water is applied to the convex side of a warped sheet of currugated paperboard as the sheet leaves a corrugator. As this wetted convex side of the paperboard sheet dries, the fibers shrink to a greater extent than they had originally thereby pulling the sheet to a non-warped, flat condition. Thus, by removing the warp from the warped corrugated paperboard, this board can be utilized as acceptable quality board rather than being scrapped as was previously necessary.

United States Patent n91 Taylor 1 Ju1y30, 1974 REMOVAL OF WARP FROM CDRRUGATED PAPERBOARD [75] Inventor: Larry D. Taylor, Circleville, Ohio [73] Assignee: Owens-Illinois, Inc., Toledo, Ohio [22] Filed: June 7, 1973 [21] Appl. No.: 367,698

Related U.S. Application Data [62] Division of Ser. No. 244,450, April 17, 1972,

abandoned.

[52] U.S. Cl. "93/111, 162/197, 162/270 [51] Int. Cl 1331f 7/00 [58] Field of Search 93/1 R; 162/197, 270; 117/152; 118/239, 249

[56] References Cited 7 UNlTED STATES PATENTS 3,004,880 10/1961 Lord 156/210 X 3,564,724 2/1971 Keyes et a1 162/270 UX OTHER PUBLICATIONS Tappi, Vol. 47, No. 7 July, 1964, Pages 168A, 169A, and 170A. l

"P2571216 sxmtner iiyik Assistant ExaminerJames F. Coan Attorney, Agent, or FirmA. J. Steger [57] ABSTRACT A new method and apparatus is provided by this invention for removing the warp from warped sheets of corrugated paperboard in'corrugated box plants. In accordance with this invention, water is applied to the convex side of a warped sheet of currugated paperboard as the sheet leaves a corrugator. As this wetted convex side of the paperboard sheet dries, the fibers shrink to a greater extent than they had originally thereby pulling the sheet to a non-warped, flat condition. Thus, by removing the warp from the warped corrugated paperboard, this board can beutilized as acceptable quality board rather than being scrapped as was previously necessary.

1 Claim, 1 Drawing Figure BACKGROUND OF THE INVENTION This invention relates to corrugated paperboard and, more particularly, it relates to the problem of eliminating undesirable warp from warped sheets of corrugated paperboard.

The corrugated paperboard industry has long been plagued with the problem of warped or bowed sheets of corrugated paperboard. This problem of warp in corrugated paperboard may be caused by a number of different conditions during the formation of corrugated paperboard. For example, unequal drying is a frequent cause of warped or bowed sheets of corrugated paperboard. This unequal drying condition' will result when one side dries faster than the other to thereby result in greater shrinkage of fibers on one side so as to pull the board into a bowed or warped configuration. Another situation in which warped paperboard results is that where dissimilar liner layers are utilized. For example, if one liner layer is formed of a much heavier weight paper than the opposite liner layer, different drying patterns can result thereby causing warped paperboard.

This resulting condition of warped corrugated paperboard has resulted in a considerable waste of otherwise -useful corrugated paperboard and a serious economic loss for the corrugated paperboard manufacturers.

Typically, warped corrugated paperboard is baled and discarded, used for scrap sheets, or cut up into smaller sheets for a less profitable order. Therefore, it is apparent that there has been a long-felt need in the corrugated paperboard industry for a method to remove the warp from warped corrugated paperboard so that it can be salvaged for normal usage.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a new method and apparatus for removing the warp from warped corrugated paperboard in corrugated box plants.

In the unique method of this invention water is applied to the convex side of the warped sheet of corrugated paper as the sheet leaves a corrugator. This wetted convex side of the paperboard sheet is then dried so that the fibers shrink to a greater extent than they .had originally thereby pulling the sheet to a nonwarped, flat condition. The apparatus of this invention includes a water application roll which applies a controlled amount of water to the convex side of the warped sheet of corrugated paperboard as the warped sheet is directed over a water reservoir from which the water application roll receives its water.

Thus, by successfully removing the warp from the warped corrugated paperboard in accordance with the method and apparatus of this invention, the resulting unwarped corrugated paperboard can be utilized as acceptable quality paperboard rather than being scraped or used as lower quality paperboard as was previously necessary.

Other objects, features, and advantages of this invention will become apparent upon reference to the following detailed description of the invention and the drawing illustrating a preferred embodiment thereof.

IN THE DRAWING The FIGURE is a schematic view of the apparatus of this invention for removing the warp from a warped sheet of corrugated paperboard.

DETAILED DESCRIPTION OF THE INVENTION' In the drawing, the numeral 10 is utilized to indicate generally the apparatus of this invention which is utilized to remove the warp from a warped sheet of corrugated paperboard 12. The apparatus 10 includes a first conveyor device 14 which incorporates a plurality of belts 16 revolving about a pair of spaced rollers 18. This first conveyor device 14 may be placed adjacent to a corrugator (not shown) so that it is adapted to directly receive warped sheets of corrugated paperboard such as the warped sheet 12. The warped sheet 12 is conveyed by the first conveyor device 14 to a pair of feed rolls 20 which drive it forward to a location occupied by the warped sheet indicated as l2a. The warped sheet 12a has an upper concave side 22 and a lower convex side 24 and is shown in position to receive a water application treatment on its convex side 24. A water reservoir 26 is provided to contain an adequate supply of water 28. A water application roll 30 is mounted above the water reservoir 26 and positioned so as to rotate in contact with the water 28 in the reservoir 26 on one side and in contact with the convex side 24 of the warped sheet 12a onthe other side. A rotating doctor roll 32 is positioned above the reservoir 26 and located adjacent to the circumference of water application roll 30 to control the amount of water on the water application roll 30. A floating pressure roll 34 is pivotally mounted above the water application roll 30 by means of a lever arm 36 which is attached to a frame 38. It is the function of the floating pressure roll 34 to maintain the warped sheet 12a in contact with the water application roll 30 as the sheet 12a is advanced by means of feed rolls 20 between the water application roll 30 and the floating pressure roll 34. As the warped sheet 12a is fed by feed rolls 20 into contact with the water application roll 30, a controlled amount of water is applied to the lower convex'side 24 of the warped sheet 12a by means of the water application roll 30. This water application treatment thereby results only in the convex side 24 of the warped sheet 12a being subjected to the application of water. After the sheet 12a belts 42 revolving about a pair of spaced rollers 44. As i the sheet 12a is directed onto the second conveyor device 40, it assumes the position shown by the unwarped or flat sheet 12b. This transformation from the warped sheet shown at 12a to the flat sheet shown at 12b occurs when the fibers on the wetted convex side 24 of the sheet 12a dry and shrink to a greater extent than they had originally thereby pulling the warped sheet 12a to the unwarped or flat condition as shown by sheet 12b. The unwarped or flat sheet 12b is then conveyed by the second conveyor means 40 to a suitable stack 46 of unwarped sheets which have been salvaged for normal usage.

Therefore, it can be seen from the preceding description, that the application of a controlled amount of water to the convex side of a warped sheet of corrugated paperboard will cause the wetted fibers on this convex side to shrink as they dry to a greater extent than they had originally to thereby result in a pulling of the sheet to an unwarped, flat condition. It should be understood that the amount of water applied to the convex side of the warped sheet will be determined by the severity of the warped condition of the sheet. For example, a severely warped sheet may require the application of more water than would a slightly warped sheet. The quantity of water to be applied to the convex side of the warped sheet can, of course, be regulated by adjusting the position of the doctor roll 32 relative to the water application roll 30. It should also be understood that the method and apparatus of this invention is well suited to be run continuously to rapidly treat a plurality of warped sheets of corrugated paperboard so that they can be salvaged for normal usage.

I claim:

1. A method of salvaging warped sheets of corrugated paperboard by removing the warp from the individual warped sheets, said individual warped sheets having generally convex and concave sides, said method comprising the steps of:

applying water to a water application device; regulating the quantity of water on said water application device; conveying the individual warped sheets of corrugated paperboard into contact with the water application device; applying a regulated quantity of water directly to the convex side of said warped sheets of corrugated paperboard so as to wet the fibers on the convex side of said warped sheets of corrugated paperboard; and conveying said wetted sheets of corrugated paperboard away from the water application device so that the wetted fibers on the wetted, convex side dry and shrink, thereby pulling the sheets to a nonwarped, flat configuration. 

1. A method of salvaging warped sheets of corrugated paperboard by removing the warp from the individual warped sheets, said individual warped sheets having generally convex and concave sides, said method comprising the steps of: applying water to a water application device; regulating the quantity of water on said water application device; conveying the individual warped sheets of corrugated paperboard into contact with the water application device; applying a regulated quantity of water directly to the convex side of said warped sheets of corrugated paperboard so as to wet the fibers on the convex side of said warped sheets of corrugated paperboard; and conveying said wetted sheets of corrugated paperboard away from the water application device so that the wetted fibers on the wetted, convex side dry and shrink, thereby pulling the sheets to a non-warped, flat configuration. 